This Twaggie is based on a Tweet by @thesulk. If true, it would go a long way toward explaining why Rachmaninov's music is so difficult for us mere mortals to play. Link
Previously at Neatorama: Another possible explanation.
If that is true, then why do photos of Rachmaninoff show his hands having 5 digits each? "Along with his musical gifts, Rachmaninoff possessed physical gifts that may have placed him in good stead as a pianist. These gifts included exceptional height and extremely large hands with a gigantic finger stretch. This and Rachmaninoff's slender frame, long limbs, narrow head, prominent ears, and thin nose suggest that he may have had Marfan syndrome, a hereditary disorder of the connective tissue..." (wikipedia)
I love Rachmaninov.